On Wed, Oct 06, 2004 at 10:36:41AM -0400, Ed L Cashin wrote: > In his 2000 OLS talk, Ken Preslan talks about some older software like > "pool" and "memexp". I want to make sure I understand how things have > changed since 2000. Are the following paragraphs correct? > > Pool is software that the GFS folks created before LVM was ready. > LVM does volume management today, and pool is obsolete. Well, pool is still in production use but will be substituted by CLVM further down the road. CLVM is a superset of LVM2 and you can download it with the LVM2 archive. It comes with builtin pool support, so that migrations to CLVM from pool are going to happen smoothly. > > One of the features of pool that he mentions is also in LVM: > identifying physical block devices by their contents instead of > their location. The example he gives is of a SCSI drive in a > fiber channel network, where adding a drive in one room can change > the LUN of a drive in another room. Pool allowed tracking of > drives regardless of their location. LVM does the same thing. Yes. Everything is identified using UUIDs (PVs, VGs, LVs). UUIDs on PVs give you location independency of drives. > > The memexp locking module that was new at the time of the 2000 OLS > talk was designed to use RAM exported by fancy storage hardware for > coordinating locking. A single node could stand in, though, taking > the place of the fancy RAM-exporting storage hardware. Today, most > GFS installations use DLM instead. > > Preslan mentions that after acquiring a lock, a node must "heartbeat > the drive" because the locking state is on the storage hardware. > > How is that done these days? Does a lock owner heartbeat the lock > master or does cluster management take care of this issue? > > -- > Ed L Cashin <ecashin@xxxxxxxxxx> > > -- > > Linux-cluster@xxxxxxxxxx > http://www.redhat.com/mailman/listinfo/linux-cluster -- Regards, Heinz -- The LVM Guy -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat GmbH Consulting Development Engineer Am Sonnenhang 11 56242 Marienrachdorf Germany Mauelshagen@xxxxxxxxxx +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
